Electric alarm



2 Sheets-Sheet 1.

(No Model.)

. J. J. WOOD.

ELECTRIC ALARM- No. 325,639. Patented Sept. 1, 188 5.

fly. 1.

a0 5 20 5 Ho 35 5 8 lllll t a g, mm 1 jzvenzon- CZMYZ.

(No Model.) 2 Sheets-Sheet 2.

- J. J. WOOD.

ELECTRIC ALARM. No. 325,639. Patented Sept. 1, 1885.

205 5236615655 v 150716222021- 7 i 7 *W To all whom it may concern.-

.plish this heretofore a magnet has been ar- UNITED STATES PATENT OFFICE,

JAMES J. \VOOD, OF BROOKLYN, NEV YORK.

ELECTRIC ALARM.

QPE CIFICATION forming part of Letters Patent No. 325,639, dated September 1, 1885.

' Application filedOctcber 4, 18i-3 Yo model.)

Be it known that I, JAMES J- WOOD, of Brooklyn, Kings county, New York, assignor to THE FULLER ELECTRICAL COMPANY, of New York city, have invented certain new and useful Improvements in Electric Circuits, of which the following is a specification.

My improvement applies more particularly to are circuits having a number of lamps arranged in series, and each having an automatic cut-out or shunting device to cut any lamp out of circuit when it becomes defective; and the object of my invention is to provide a vibratingsignal or alarm which will be op-. erated by abnormalchange or increase in the current due to thccuttiug out of one or more lamps, and which shall continue to so vibrate until the current is adjusted to the change, whereby the engineer will be at once-informed of the extinguishment of any lamps in the circuit, and will be enabled to adjust the current to the number of lamps remaining in actionwithout leaving the engine-room. To accom ranged in the main circuit with its armature arranged, when attached, to close a batterycircuit and ring a vibrating electric bell in said battery-circuit. The addition of a bat-' tery-circuit is, however, objectionable,-and my invention dispenses entirely with the same and adapts the main lighting-circuit to operate a vibrating bell by simply a variation in the strength of the current in the circuit without at any time breaking the circuit. improvement, therefore, I arrange the bellringiug or signaling magnet in the directlightcircuit, and its armature is so adjusted as to be nearly balanced before the magnet, and to yield or respond only to an abnormal-change in the attraction of the magnet due to an abnormal increase or decrease of current strength in the circuit, and to its armature is connected a contactmaken-which, when the armature is attracted, closes a shunt in the main circuit around the magnet, thereby causing an alternate attraction and retraction of the armature and a sounding of the alarmso longas the abnormal condition continues without at any time breaking the light-circuit. Whemhowever, the current is adjusted to the change in the circuit, the armature ceases to vibrate, but

In my willagain vibrate asisoon "as any change occurs in the condition of the circuit until the current is again adjusted to the change, as will be understood.

My invention therefore consists, mainly.- in

the features here outlined, as hereinafter full y set forth. In addition to the automatic alarm I also employ a novel and simple galvanometer or current-gage to indicate visibly any increase or decrease in-the current strength; but this device .I do not claim in this application.

In the drawings annexed, Figure 1 presents a diagram of a complete electric-light circuit equipped with my improvements; and Fig. 2 represents part of such a circuit, illustrating a modification of my invention.

I would first note that in order to show an increase or decrease of current separate indicators or alarms of slightly-difierent constructions would be required, one being adapted to sound by an increase of current and the other by a decrease of current. Fig. 1 shows an alarm adapted to sound by an increase of current strength, while Fig. 2 shows the alarm adapted to sound by decrease of strength, their prineiple'of action being, however, the same. As, however, a decrease of strength would do no injury in the circuit and would be always instantly indicated on the gage, it will therefore be hardly necessary to provide an alarm to indicate such decrease, whereas an increase of strength might be seriously injurious in a short time, and hence the engineer should be immediatelynotified of the fact by an audible alarm. Hence in most cases the alarm to indicate increase only will be necessary in connection with the gage, and I shall therefore first describe said alarm, which is shown in Fig. 1. r

Referring toFig. l of the drawings, N Sindicates the generator of electricity, and a a the electric circuit which proceeds therefrom, in which circuit is included a series of are lamps, indicated by b 0, arranged in the usual manner in series, as shown. Each of these lam 's is provided with an automatic cutout or shunting device, as indicated, which consists of a magnet, d, of high resistance in a shunt, 0, around each lamp, and a safetyswitch, f, in a normally-open parallel shunt,

IOO

h, of low resistance, which shunt-n1agnet,when

lamps burning properly. The lamps will of course all be adjusted as usual to give a uniform length of arc, orwnearly so, and the generator will be set to produce a maximum current proportional to the number of lamps, so

as to properly maintain the whole series in regular and etfieientaction. If, however, one or more of the lamps should now become defective in any way, and therefore become shunted out of the circuit by the action of the cut-out, the resistance of the entire circuit would become suddenly and materially reduced, while the current from the generator would remain at its maximum; and hencethe currentwould now be out of proportion to the remaining lamps, which would receive an excessive amount of current, and this excessive current would be likely to derange the action of the lamps or overheat parts of the circuit if allowed to continue. It is therefore obviously desirable to provide the circuit with a means for indicating and alarming when any such change occurs, as before described, so that the engineer or attendant canreadily adjust the circuit or the generator to the change beforeany appreciable derangement occurs in any part of the lighting apparatus. My iir vention therefore provides for this in an improved manner, and includes a device to give an audible alarm or signal to show the fact that a change has occurred, as well as an electrical gage to show the degree of change which has occurred.

In the drawings, A indicates the alarm or signal device, and B the electrical gage. In

the alarm, i indicates a strong electro-magnet.

of low resistance, whose coils are introduced directly in the light-circuit, and in front of the poles of the magnet is pivoted an armature-lever,'k, whose extremityforms a bellhammerto strike the bell-Z or operate any other equivalent sounder or signal. The armature is provided with a retracting-spring, m, or equivalent retracting device, which tends constantly to retract the armature against a stop, n, and it is also provided with a contactmaker, o,which,when the armature is retracted, is out of contact, as shown; but if the armature is attracted the cont-act-maker will 4 make contact with a seat or stop, 1), which is introduced in one limb of the light circuit, while a wire or conductor, 1", extends from the armature or the contact-maker to the other limb of the circuit. Hence, if the armature be attracted, the contact-maker will close a shunt or short circuit through the wire r, so as to divertthc main current from the mag-,

net, and will thus demagnetize or greatly weaken the magnet; consequently the armature will immediately be retracted after its attraction, and in so doing the shunt will be broken and the full current again sent throughthe magnet, which will again attract its armature, and so on alternately,producing an energetic vibration of the armatureby means of the. lighting-current, yet at notime breaking the lighting-current.

Now, when the circuit is in its normal maximum condition-that is, all the lamps being in action and the strength of current at its normal maximumthe magnet 73 will pos sess acorresponding normal strength,.tending to attract its armature k. The retracting-spring m is, however, so adjusted as to just over-balance this normal attraction of the magnet; consequently while the circuit remains in its normal condition,with the current strength normal, the armature will remain in its retracted position, as shown in the drawings. If, however, the current should now increase in strength by reason of the cutting out of any lamps in the circuit, the attraction of the magnet 13 would immediately become abnormally increased, andwould thus overcome the force of the retracting'spring m, and hence the armature would become energetically vibrated, and the bell thereby rung, as before described. The ringing of the alarm would immediately call the attention of the engineer to the fact that a change had occurred in the circuit, and he would then proceed to reduce the current strength to its normal, either by switching resistances into the circuit or adjusting the commutatorbrushes on the generator so as to reduce the current until the bell stopped vibrating,which would show that the current was reduced to its normal condition suited to the changed condition of the circuit, at which point the armature would fall back to its retracted po sition, and so remain until another change occurred in the circuit, as will be under stood. I

It will thus be seen that by the means described a mere increase of currentin the lightcircuit will cause a vibrating bell or signal to be set in action by the force of said increased current, yet without at any instant breaking or in the least way affecting the continuity of the light circuit, which is an important advantage over the alarm heretofore-employed in light-circuits.

Now, while the alarm A is always sounded when any abnormal relative increase of current occurs in the circuit, the gage B will show the amountof this increase, so that the engineer will know at a glance the amount of resistance toswitch into the circuit or the degree of adjustment required at the commutator ot' the generator in order to restore the current to itscorrect relative force. In this gage,'t indicates anelectro-magnet of horseshoe form,

the coils of which are in the light-circuit, as

IIO

shown, while the opposing faces of the poles are hollowed or curved out to present concave eccentric faces, as shown. Between these concave faces is arranged an armature, 3 prefer- .ably of soft iron,disposed radially to the polar faces and pivoted at the middle, with its opposite extremities approaching the eccentric faces of the poles, the extremities being preferably curved concentric with the curve of the polar faces, while the curve of the polar faces is eccentric to the pivot of the armature, as shown. To the armature is attached a long index -finger, u, which is movable over a graduated are, c. A retracting-spring,w, tends constantly to bring the index-finger against a stop, :17, and up to the zero of the scale, in which position thearmature will be swayed to its limit in the retracted direction, in which its extremities will he opposite the receding or distant end of the polar faces. ever, tends to swing the armature around toward the opposite position, where the ends of the armature will approach the near ends of the eccentric curves; consequently the stronger the attraction is the more will the armature The attraction ofthe poles, howbe swayed around toward the approaching ends of the curves and the farther will the index'finger move out on the scale, and this increase of attraction, of course, represents relative increase of current, so that the position of the index-finger on the scale indicates the current strength in the circuit. The graduations on the scale will represent, of course, certain electrical values, and a certain number of degrees will be known to represent a current strength suited to a certain number of lamps. When, therefore, the circuit is in normal maximum action, theindeX-finger will stand at a certain determined figure on the scale, as shown, and this figure will of course vary in different cases, according to the nature or length of the circuit; but when the proper degree is determined upon for any particular circuit the finger should always stand at that degree, or thereabout, when the circuit is'in full action. If, therefore, a relative increase of current should at any time occur in the circuit by reason of the cutting out of any lamps, as before referred to, the alarm will of course immediately sound, and the index-finger of the gage will move out on the scale. By now observing the degree at which the finger stands the engineer will know approximatelyhow many lamps have become out out, and he will know at once what adjustments are required to bring the finger back: to its normal position, and when such adjustments are made and the finger thus brought back to its normal position at the same time that the alarm stops ringing the engineer will then know that his circuit is correctly adjusted to the change that has occurred, and he can afterward go over the circuit at his convenience to find and remedy the defective lamps;

eccentric curve .on the on the armature, as will be readily seen,

\Vhenthe engineer has found the defective lamps and corrected them, he may then'switch them into the circuit, which will of course cause the current to relatively decrease in strength, and hence the index finger of the gage will fall back from its normal position. The engineer may then raise the strength of current by switching out the resistance from the circuit or adjusting the commutator-brushes back toward their maximum position until the finger of the gage is brought back to the normal position, which wilLshow that the current is correctly adj ustcd for the lamps in action. Hence by these simple additions to the lighting-circuit the engineer will always be informed of the condition of his circuit, and will be enabled to readily adjust it as changes occur before any injury can happen to any part of the apparatus, which is a very desirable and a very important matter, as arc-lighting is now conducted in extensive circuits.

In case it is thought necessary to provide an alarm to indicate abnormal decreases of current strength, it :will be constructed as shown in Fig. '2, differing but slightly fromthat already, described. In Fig. 2 the corresponding parts of the alarm shown in Fig. 1,

and already described, are lettered similarly, and it will be thereforenoted that the elements of the device are the same, but that the bell is placed outhe retracting side of the hammer, and the retracting-spring is so adjusted that the armature is normally attracted and the shunting contact .0 normally closed. The adjustment will be such, however, that the pressure on the contact will be slight, and hence only aslight or determinate amount of current will pass through the shunt, and while. the current strength in the circu it is normal, the magnet will therefore possess a normal attraction, to just hold the armature in its attracted position; but not with suflicicnt energy to keep the contact so firmly closed as to divert any great amount of the current from the magnet. If, however, the current should decrease abnormally in the circuit, the retractingspring will immediately overbalance the weakened attraction of the'magnet, and thus withdraw the armature and sound the bell, which movcment will of course entirely separate the contacts 0 p, and thus causethc entire current to pass through the magnet, which will thus cause it to forcibly attract its armature and again close the contact, and in turn cause theretracting movement, thus producing a positive vibration of the armature and a ringing of the hell by virtue of the said decrease in the current without destroying the continuity of the light-circuit at any instant.

It will be seen that these improvements will apply to circuits for electric motors as well as for electriclamps. In fact, all are lamps containing elect ric-motor mechanisms may be considered as electric motors as well as electric lights, since the electric current produces in them mechanical power as well as light.

I reserve the subject of the curm nt-gage for 4 contact 0 0, and retracting device '11, adjusted a subsequent application. l as described, subst aptially as and for the pur- What I claim ispose set forth. The combination of the electric circuit a, JAMES J. WOOD, 5 having lamps b b, or their equivalents, and Witnesses:

their individual cut-outs, with the magnet i, JNo. E. GAVIN,

its armature k, and sounder Z, the shunt-p 0 1', CHAS. M. HIGGINS. 

